System and method for monitoring the status of one or more components of an electrical machine

ABSTRACT

A monitoring apparatus configured for monitoring a carbon brush of a brush holder assembly of an electrical machine. The monitoring apparatus may include a flexible sensor and a signal processing circuit for processing a signal received from the flexible sensor. The flexible sensor may have an electrical resistance that varies based on a radius of curvature of the flexible sensor, wherein the radius of curvature of the flexible sensor may be associated with a deflection of a spring providing a force to engage the carbon brush with a rotating component of the electrical machine. The signal processing circuit may be coupled to the sensor and may be configured to determine a measure of a wear state of the carbon brush using information about the variable resistance of the flexible sensor.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation application of U.S. patentapplication Ser. No. 13/802,969, filed Mar. 14, 2013, the completedisclosure of which is herein incorporated by reference.

TECHNICAL FIELD

The disclosure generally relates to monitoring systems for monitoringbrushes and brush holder assemblies that may be used in electricaldevices and/or slip ring assemblies. More specifically, the disclosurerelates to monitoring apparatus, assemblies, systems and methods ofmonitoring the wear of a brush in a brush holder assembly and/or thecondition of a slip ring of an electrical device using a flex sensor.

BACKGROUND

A purpose of a brush in an electrical device is to pass electricalcurrent from a stationary contact to a moving contact surface, or viceversa. Brushes and brush holders may be used in electrical devices suchas electrical generators, electrical motors, and/or slip ringassemblies, or sliding connection applications, for example, slip ringassemblies on a rotating machine such as a rotating crane or a linearsliding connection on a monorail. Brushes in many electrical devices areblocks or other structures made of conductive material, such asgraphite, carbon graphite, electrographite, metal graphite, or the like,that are adapted for contact with a conductive surface or surfaces topass electrical current. Electrically conductive leads or shunts extendfrom the brush to provide an electrical pathway to and/or from the brushfrom another conductive member.

In some designs, a brush box type brush holder, or other type of brushholder, may be used to support a brush in contact with a moving contactsurface of an electrical device during operation. The brush and brushbox may be designed such that the brush can slide within the brush boxto provide for continuing contact between the brush and the movingcontact surface contacted by the brush. During operation an anomalousand/or threshold condition may occur, which may be indicative that oneor more components of the electrical device may need to be replaced, oneor more components of the electrical device may require inspection orattention, and/or maintenance may need to be performed. For example, ananomalous and/or threshold condition may indicate that one or more of abrush, brush holder, spring, shunt, commutator, collector ring, and/orother component may need to be replaced, one or more of a brush, brushholder, spring, shunt, commutator, collector ring, and/or othercomponent may need to be inspected, and/or maintenance may need to beperformed. It would be advantageous to monitor one or more components ofan electrical device in order to observe the occurrence of an anomalousand/or threshold condition. Furthermore, it would be advantageous toalert an operator and/or technician of the occurrence of an anomalousand/or threshold condition and/or schedule technician intervention.

SUMMARY

The disclosure is directed to monitoring apparatus, assemblies, systemsand methods of monitoring the wear of a brush in a brush holder assemblyand/or the condition of a slip ring of an electrical device using a flexsensor. Accordingly, one illustrative embodiment is a monitoringapparatus configured for monitoring a carbon brush of a brush holderassembly of an electrical machine. The monitoring apparatus may includea flexible sensor and a signal processing circuit for processing asignal received from the flexible sensor. The flexible sensor may havean electrical resistance that varies based on a radius of curvature ofthe flexible sensor, wherein the radius of curvature of the flexiblesensor may be associated with a deflection of a spring providing a forceto engage the carbon brush with a rotating component of the electricalmachine. The signal processing circuit may be coupled to the sensor andmay be configured to determine a measure of a wear state of the carbonbrush using information about the variable resistance of the flexiblesensor.

Another illustrative embodiment is a system for monitoring a wear stateof one or more carbon brushes associated with an electrical machineand/or a wear state of a rotating component of the electrical machine.The system may include one or more brush holder assemblies associatedwith the electrical machine and a site monitor for receiving wear stateinformation from the one or more brush holder assemblies. Each of thebrush holder assemblies may include a carbon brush, a spring adjacent tothe carbon brush, a flexible sensor positioned adjacent to the springand a wear state monitor coupled to the flexible sensor. The spring maybe configured to provide a force to the carbon brush such that thecarbon brush engages a rotating component of the electrical machine. Theflexible sensor may have an electrical resistance that varies based on aradius of curvature of the flexible sensor. The radius of curvature maybe representative of a physical position and/or movement of the carbonbrush. By monitoring the physical position, and/or the movement of thecarbon brush, such as by monitoring a measure (e.g., a resistance, avoltage, a current, etc.) associated with the radius of curvature of thebend sensor, a wear state of the carbon brush and/or a wear state of therotating component of the electrical machine may be determined. The wearstate monitor may be configured for determining a measure of a wearstate of the carbon brush using the variable resistance of the flexiblesensor. The site monitor may be communicatively coupled with the wearstate monitor of the one or more brush assemblies for receiving wearstate information about the carbon brushes of the one or more brushassemblies and communicating the wear state of the one or more carbonbrushes to a user.

An illustrative method for monitoring a wear state of one or morecomponents of an electrical device may include obtaining a variableresistance value from a flexible resistor for sensing the movement of acarbon brush in relation to a rotating component of the electricaldevice, comparing the variable resistance value to a threshold value todetermine a wear state of the carbon brush, and communicating anindication of the wear state of the carbon brush to a user.

Another illustrative embodiment may be a brush holder assembly having anintegral sensor for monitoring a wear state of a carbon brush or anassociated rotating component of an electrical machine. The brush holderassembly may include a carbon brush, a spring for providing a force toengage the carbon brush with a rotating component of an electricalmachine and a wear state sensor. The wear state sensor may include abend sensor, a comparator, an indicator and a communication circuit. Thecomparator may compare a signal received from the bend sensor to apredetermined threshold value to determine a wear state of at least oneof the carbon brushes and the rotating component of the electricalmachine. The indicator may provide an indication of the wear state of atleast one of the carbon brushes and the rotating component of theelectrical machine to a user. The communication circuit may communicateinformation about the wear state of at least one of the carbon brushesand the rotating component of the electrical machine to a site monitorproximal to the electrical machine.

The above summary of some example embodiments is not intended todescribe each disclosed embodiment or every implementation of theaspects of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The aspects of the disclosure may be more completely understood inconsideration of the following detailed description of variousembodiments in connection with the accompanying drawings, in which:

FIG. 1 shows an illustrative view of an exemplary brush monitoringsystem;

FIGS. 2A and 2B are perspective views of the illustrative wear statesensor of FIG. 1.

FIG. 3 shows a side view of the brush holder assembly including theillustrative wear state sensor of FIGS. 1 and 2.

FIG. 4 is a block diagram representation of the illustrative wear statesensor of FIGS. 1-3.

FIGS. 5A and 5B are perspective views of an illustrative flexiblesensor.

FIGS. 6A and 6B show side views of an illustrative brush holder assemblyhaving a particular wear state of a carbon brush.

FIG. 7 is a block diagram representation having an illustrative sitemonitor.

FIG. 8 illustrates an exemplary bus of mounting blocks and brush holderassemblies of an electrical machine utilizing a unique identificationsystem to reference a position of a brush holder and associated brush onthe electrical machine.

FIG. 9 shows a graph of an illustrative voltage associated with thevariable resistance of the flexible sensor associated with the wearstate of a carbon brush.

FIG. 10 shows a graph of an example of a transient voltage signalillustrative of a condition of a rotating component of an electricalmachine.

FIG. 11 shows an illustrative method for monitoring a wear state of oneor more components of an electrical device.

While the aspects of the disclosure are amenable to variousmodifications and alternative forms, specifics thereof have been shownby way of example in the drawings and will be described in detail. Itshould be understood, however, that the intention is not to limitaspects of the disclosure to the particular embodiments described. Onthe contrary, the intention is to cover all modifications, equivalents,and alternatives falling within the spirit and scope of the disclosure.

DETAILED DESCRIPTION

For the following defined terms, these definitions shall be applied,unless a different definition is given in the claims or elsewhere inthis specification.

All numeric values are herein assumed to be modified by the term“about”, whether or not explicitly indicated. The term “about” generallyrefers to a range of numbers that one of skill in the art would considerequivalent to the recited value (i.e., having the same function orresult). In many instances, the term “about” may be indicative asincluding numbers that are rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numberswithin that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4,and 5).

Although some suitable dimensions, ranges and/or values pertaining tovarious components, features and/or specifications are disclosed, one ofskill in the art, incited by the present disclosure, would understanddesired dimensions, ranges and/or values may deviate from thoseexpressly disclosed.

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. As used in this specification and theappended claims, the term “or” is generally employed in its senseincluding “and/or” unless the content clearly dictates otherwise.

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The detailed description and the drawings, which are notnecessarily to scale, depict illustrative embodiments and are notintended to limit the scope of the disclosure. The illustrativeembodiments depicted are intended only as exemplary. Selected featuresof any illustrative embodiment may be incorporated into an additionalembodiment unless clearly stated to the contrary.

FIG. 1 shows an illustrative view of an exemplary brush monitoringsystem 100 that may include a brush holder assembly 110, a site monitor120 and/or a remote monitoring site 140 including a remote monitoringdevice 150, 160. In some cases, the brush holder assembly 110 maysubstantially resemble a brush holder assembly as described in U.S. Pat.No. 7,034,430, entitled “BRUSH HOLDER APPARATUS, BRUSH ASSEMBLY, ANDMETHOD”, which is herein incorporated by reference in its entirety.However, the illustrative brush monitoring system 100 may be amenable toany of various brush holder assembly configurations. Thus, the intentionis that the illustrative brush monitoring system 100 may be used inconjunction with any desired brush holder assembly configurations of anelectrical device, such as an industrial electrical generator. Forexample, the illustrative brush monitoring system 100 may be used withbrush holder assemblies, brush holders and/or brushes disclosed in U.S.Pat. Nos. 6,731,042; 5,753,992; 5,621,262; 5,463,264; 5,397,952; and5,256,925; each of which is incorporated herein by reference.

The brush holder assembly 110, for example as shown in FIG. 1, mayinclude a brush holder 22, such as a brush box, surrounding a brush 24on several sides and including a plurality of guiding surfaces forguiding linear or longitudinal movement of the brush 24. In someembodiments, the brush holder 22 may not take on the form of a box, butmay include one or a plurality of guiding surfaces, such as channels,posts or columns, abutting and/or encompassing one or more sides of thebrush 24 and/or extending into or through the brush 24, or a portionthereof, for guiding linear or longitudinal movement of the brush 24.

The brush holder 22 may be secured to a mounting beam 26 configured andadapted to be mounted to another structure, such as a mounting block 70.The brush holder assembly 110 may be configured to place the brush 24 incontact with a conductive surface 12, such as a surface of a rotatingcomponent 15 of an electrical machine, such as a collector ring, a slipring, or a commutator, and conduct current therefrom. The brush 24 mayextend from the lower edge of the brush holder 22 such that a wearsurface of the brush 24 engages the conductive surface 12. The mountingbeam 26 may include an over-center engagement mechanism, a slotted orchanneled engagement mechanism for sliding engagement, or othermechanism for easily engaging and disengaging the brush 24 from aconductive surface 12. In other embodiments, the brush holder assemblymay include a brush holder rigidly mounted to another structure holdingthe brush holder stationary, or mounted to another structure in anydesired arrangement. For example, in some embodiments the brush holdermay be bolted or welded to a stationary structure. Some such brushholders are disclosed in U.S. Pat. Nos. 6,731,042; 5,753,992; 5,621,262;5,463,264; 5,397,952; and 5,256,925; which are incorporated herein byreference.

As shown in FIG. 1, the mounting beam 26 may include an upper beammember 27 and a lower beam member 28 hingedly or pivotedly coupled toone another. When the upper beam member 27 and the lower beam member 28are aligned with one another (e.g., the longitudinal axis of the upperbeam member 27 is parallel with the longitudinal axis of the lower beammember 28), the brush holder 22 may be considered to be in an engaged,or locked, position such that the brush 24 may be contiguous with or incontact with the conductive surface 12. When the upper beam member 27 istilted from the lower beam member 28 (e.g., the longitudinal axis of theupper beam member 27 is oblique to the longitudinal axis of the lowerbeam member 28), the brush holder 22 may be considered to be in adisengaged, or unlocked, position such that the brush 24 may benon-contiguous with, spaced from, or otherwise not in direct electricalcontact with the conductive surface 12. The mounting beam 26 may beremovably coupled to the mounting block 70 during operation. In someembodiments, the mounting beam 26 may slidably engage with, interlockwith, or otherwise be removably coupled to the mounting block 70. Themounting block 70 may be coupled to, secured to, or otherwise extendfrom another structure which maintains the mounting block 70 stationarywith respect to the conductive surface 12, for example.

In some embodiments, a handle 21 may be attached to the brush holder 22to facilitate engagement and disengagement of the brush 24 from theconductive surface 12. For example, the handle 21 may be attached to theupper beam member 27 such that movement of the handle 21 actuates (e.g.,pivots, slides, releases) the upper beam member 27 relative to the lowerbeam member 28. The handle 21 may be a removable handle or the handle 21may be permanently attached to the upper beam member 27 or anotherportion of the brush holder 22.

Also illustrated in FIG. 1 is a spring 29, such as a constant forcespring, which provides tension to the brush 24 to bias the brush 24toward and in contact with the conductive surface 12. The spring 29 maybe attached to a portion of the brush holder 22 or the mounting beam 26of the brush holder assembly 110, for example. In some embodiments, thespring 29 may extend along one side surface of the brush 24 between thebrush 24 and the mounting beam 26 of the brush holder assembly 110.

The brush holder assembly 110 may further include a wear state monitor50 and a flexible sensor 60, wherein the wear state monitor 50 may becommunicatively coupled to the flexible sensor 60. For example, the wearstate monitor 50 may receive a signal representative of the positionand/or movement of the brush 24. In some cases, the wear state monitor50 may be positioned adjacent to the spring 29. For example, the wearstate monitor 50 may be mounted adjacent a surface of the spring 29 orotherwise with the spring 29, such as within a coil formed by the spring29, as shown in FIG. 3. The wear state monitor 50 may include one ormore indicators 55 to communicate the physical status of the brush 24,the conductive surface 12, or both. In some cases, the indicators 55 mayinclude one or more light emitting diodes (LEDs), a speaker, or acombination of LEDs and/or speakers for communicating wear stateinformation to a user. In some cases, the wear state monitor 50 may bepositioned adjacent to a surface of a component of the brush holderassembly 110, different than the spring 29. For example, the wear statemonitor 50 may be positioned on or adjacent to the brush holder 22, thelower beam member 28, the upper beam member 27, on or adjacent to one ormore shunts of the brush holder assembly 110, and/or on or adjacent tothe handle 21 of the brush holder assembly 110. In some cases, the wearstate monitor 50 may be permanently and/or removably incorporated into aportion of the handle 21 or other component of the brush holder assembly110.

The flexible sensor 60 may also be positioned adjacent to the spring 29,such that a movement of the brush 24 may cause the flexible sensor 60 toflex or otherwise change shape. For example, a proximal end of theflexible sensor 60 may be attached to a portion of the brush holder 22or the mounting beam 26 of the brush holder assembly 110 and a distalend may be attached to and/or communicatively coupled to the wear statemonitor 50. In some cases, the flexible sensor 60 may be attached to,embedded in, in contact with the spring 29 and track or follow themovement of the brush 24. For example, the flexible sensor 60 may beaffixed to a surface (e.g., an inner surface, an outer surface, etc.) ofthe spring 29. In another example, the flexible sensor 60 may bepositioned adjacent to the spring 29. As such, any movement of theflexible sensor 60 may directly correspond to movement of the brush 24.

For example, a signal corresponding to the resistance value of theflexible sensor 60 may be equivalent, proportional, or otherwiserepresentative of the linear or longitudinal movement, vibration and/ordiminution of the brush 24. In some cases, the wear state monitor 50 mayassociate a steady-state resistance value of the flexible sensor 60 witha wear state of the brush 24 and/or a transient resistance value with awear state of the conductive surface 12 and/or the rotating component15. The steady state resistance value of the flexible sensor 60 maycorrespond to a value obtained over one or more revolutions of therotating component 15 and may correspond to the position of the uppersurface of the brush 24 relative to the conductive surface 12 of therotating component 15. In some cases, the transient resistance value ofthe flexible sensor 60 may correspond to a value obtained over at leasta portion of a revolution of the rotating component 15, such as aresistance value caused by a vibration of the brush 24 caused byvariances in the conductive surface 12 of the rotating component 15. Thesteady-state electrical value (e.g., a voltage level) may be compared toone or more predetermined threshold values to determine a wear state ofthe brush 24. Similarly, the transient electrical value may beassociated with a vibration of the brush 24 and may be monitored and/orcompared to one or more predetermined thresholds to determine a wearstate of the conductive surface 12 of the slip ring or other rotatingcomponent of the electrical machine.

The flexible sensor 60 may have an electrical resistance that variesbased on a radius of curvature of the flexible sensor 60 and may producea signal (e.g., a voltage based signal, a current based signal, etc.)corresponding to the electrical resistance of the flexible sensor 60. Insome cases, the radius of curvature of the flexible sensor 60 may beassociated with a deflection of the spring 29 providing a force toengage the carbon brush with a rotating component of the electricalmachine. The electrical resistance of the flexible sensor 60 may be usedwith other electrical components to provide a signal representative ofthe electrical resistance of the flexible sensor 60. For example, theresistance of the flexible sensor 60 may be used as a component in avoltage divider circuit that is configured to provide a voltage signalthat corresponds to the variable resistance of the flexible sensor 60.In other cases, an electrical circuit associated with the flexiblesensor 60 may be configured to provide a current signal representativeof the variable electrical resistance of the flexible sensor 60.

In some cases, the brush monitoring system 100 may include a sitemonitor 120 that may be positioned near the electrical machine tomonitor the wear state of one or more brush holder assemblies 110 and/orthe wear state of the slip ring or other rotating component of theelectrical machine. The site monitor 120 may be capable of monitoringthe wear states of the brush 24 of the brush holder assembly 110. Insome cases, the site monitor 120 may be capable of monitoring themovement of the brushes 24 of two or more brush assemblies 110associated with one or more electrical machines. For example, the sitemonitor 120 may be communicatively coupled to one or more wear statemonitors 50 associated with a particular electrical machine, such as thewear state monitor 50 of the brush holder assembly 110 via acommunication link 115 (e.g., a wireless link). The site monitor 120 maybe configured to receive processed data and/or raw data providinginformation about the wear state of the brush 24 and/or the rotatingcomponent 15. For example, the site monitor 120 may receive informationabout a comparison between a value received from the flexible sensor 60and one or more predetermined thresholds, the value received from theflexible sensor 60, or both. In some cases, the communication link 115may include a radio frequency (RF) communication link, an audio-basedcommunication link (e.g., an ultrasonic communication link), and/or anoptical communication link (e.g., an infrared (IR) communication link, avisible light communication link, etc.). In some cases, the site monitor120 may be configured to predict or determine an estimated projection ofa condition of the brush 24 into the future.

In some cases, the wear state monitor 50 may be configured tocommunicate the wear state information about the brush 24 and/or therotating component 15 of the electrical machine to the site monitor 120using a predetermined schedule (e.g., once per hour, once per day, twiceper week, etc.). In some cases, the wear state monitor 50 may providethe wear state information about the brush 24 and/or the rotatingcomponent 15 of the electrical machine to the site monitor 120 inresponse to a command received from the site monitor 120 and/or theremote monitoring device 150, 160.

The site monitor 120 may output an indication of the condition and/orprojected condition of the brush 24. In some cases, the indication maybe configured to alert an operator, technician and/or other personnelthat the brush 24 and/or the rotating component 15 are sufficiently wornand/or needs to be replaced, the brush 24 and/or the rotating component15 are damaged, failure has occurred or is imminent, or othermaintenance or inspection may need to be performed. In some embodiments,the indication may be used for scheduling maintenance or inspection,sending personnel to perform maintenance or inspection, ordering and/orscheduling distribution/delivery of a replacement brush or other part,routing maintenance personnel and/or product delivery to a specifiedlocation, or arranging for other notification and/or scheduling tasks beperformed.

The brush monitoring system 100 may also be used to identify and/ornotify other key maintenance, failure of the brush holder assembly 110and/or other anomalous conditions. For example, incidents of excessheating, arcing or excess vibration, which may indicate a need toperform maintenance and/or disrupt operation of the electricalequipment, may be identified and/or assessed by one or more componentsof the brush monitoring system 100. The wear state monitor 50, the sitemonitor 120 and or the remote monitoring device 150, 160 may carry outan appropriate response to respond to an identified anomalous conditionin an attempt to rectify the anomalous condition. In some cases, anoperator may carry out an appropriate response to respond to ananomalous condition identified with the brush monitoring system 100 inan attempt to rectify the anomalous condition.

In some cases, the site monitor 120 may be communicatively coupled by awireless link 125 and/or wired link 127 to a network 130. The sitemonitor 120 may be capable of communicating information about the wearstate of one or more brushes to a remote monitoring device 150, 160 at aremote monitoring site 140 via the network 130 and one or more wired 137and/or wireless 135 communication links. The wired link 127, 137 and/orwireless link 125, 135 communication links may be configured to operateusing one or more standardized communication protocols (e.g., Ethernet,Ethernet/IP, BACnet, Modbus, LonWorks, etc.), or proprietarycommunication protocols. Examples of a remote monitoring system aredescribed in U.S. Pat. No. 7,705,744, entitled “MONITORING SYSTEMS ANDMETHODS FOR MONITORING THE CONDITION OF ONE OR MORE COMPONENTS OF ANELECTRICAL DEVICE”, and U.S. patent application Ser. No. 11/752,965entitled “BRUSH HOLDER ASSEMBLY MONITORING APPARATUS, ASSEMBLY, SYSTEMAND METHOD” and has the U.S. Patent Publication No. 2008/0291273 whichare herein incorporated by reference in their entirety. The remotemonitoring site 140 may include one or more remote monitors, such as apersonal computer 160, a workstation, a laptop, a tablet 150, a smartphone or the like, for collecting data and/or analyzing data receivedfrom one or more user sites.

The remote monitoring devices and/or site monitor 120 may be integratedinto a maintenance program for a brush holder assembly 110, such thatthe site monitor 120 may be configured to monitor at least a conditionof one or more components of the brush holder assembly 110. To do so,the remote monitors and/or the site monitor 120 may be configured toidentify each brush holder assembly 110 on a particular machine or at aparticular site and/or store an installation date and any servicingdates for each brush holder assembly 110. In some cases, one or moreparameters received from the wear state monitor 50 associated with abrush holder assembly 110 may be monitored over time to determinetrending information about a brush 24 and/or a rotating component 15 ofthe electrical machine. For example, the site monitor 120 and/or theremote monitors may determine trend information, that may include anaverage lifetime for a brush 24 installed in a particular brush holderassembly 110 and/or for a particular installation position on anelectrical machine. The site monitor 120 and/or the remote monitors maybe configured to store information about the position of a brush (e.g.,a resistance value of the flexible sensor 60), when the brush holderassembly 110 is first installed on an electrical machine. By monitoringthe initial position each time a brush 24 is replaced in the brushholder assembly 110, information may be gathered about a wear state ofthe rotating component 15. For example, a slip ring, or other rotatingcomponent of the electrical machine, may have an initial outer diametermeasurement. Over time, with wear including normal wear and/or due toenvironmental conditions (e.g., humidity, temperature, contaminantsincluding abrasives, etc.) a wear state associated with the thicknessand/or outer diameter of the rotating component 15 may be measuredand/or predicted. In some cases, preventative measures to improve thelifetime of the brush 24 and/or the rotating component 15 may beobtained by analysis of the information received from the one or morewear state monitors 50. For example, a user may be advised to adjust oneor more environmental conditions for a space near the electricalmachine, such as a temperature, a humidity level and/or a contaminantlevel.

FIGS. 2A and 2B are perspective views 200, 250 of the illustrative wearstate monitor 50 of FIG. 1. The wear state monitor 50 may include a body210, one or more ribs 220, an opening 225 to facilitate an electricalconnection to the flexible sensor 60, one or more communicationinterfaces 230, and one or more indicators 240. In some cases, the wearstate monitor may include a user interface 260. The body 210 may begenerally cylindrical, or other such shape designed to facilitateintegration into a brush holder assembly 110 or other mounting locationwithin the brush holder assembly 110. For example, the wear statemonitor 50 may be configured to be associated with the spring 29 of thebrush holder assembly 110, as shown in FIG. 3. The body 210 of the wearstate monitor 50 may be designed to be captured within a coiled portionof the spring 29. The ribs 220, or other similar structure, may be usedto ensure the wear state monitor 50 remains mounted within the coil. Theribs 220 may be removable, or otherwise configurable, to allow the wearstate monitor 50 to be mounted within a coil of two or more differentsized springs. For example, the removable and/or configurable ribs, suchas the ribs 220, may allow the wear state monitor 50 to be mountedwithin a spring having a first width and a first coil diameter and/or aspring having a second width and/or a second diameter.

The opening 225 of the wear state monitor 50 may be used to facilitate aconnection with the flexible sensor 60. For example, the opening 225 mayallow access to an electrical connection, such as a screw terminal. Theopening 225 may have a shape corresponding to a cross-sectional shape ofthe flexible sensor (e.g., a slot), or may be another shape (e.g., acircular opening, a rectangular opening, etc.) designed to accommodatean electrical connection to the flexible sensor 60.

As discussed above, the wear state monitor 50 may be configured todetermine one or more wear states of the brush 24 and/or the rotatingcomponent 15 of the electrical machine using information obtained usingthe flexible sensor 60 (e.g., a variable resistance, a voltage signal, acurrent signal, etc.). In some cases, the wear state monitor 50 mayinclude one or more electrical connections for providing an electricalconnection to the flexible sensor 60. The electrical connections may belocated within an interior space of the wear state monitor 50, such thatthe flexible sensor 60 may be integrated with the wear state monitor 50and may extend through the opening 225 to provide a direct electricalconnection between the wear state monitor 50 and a portion of theflexible sensor 60. In some cases, one or more wires (e.g., individualwires, a shielded twisted-pair cable, a ribbon cable, etc.) may extendthrough the opening 225 to facilitate an electrical connection to theflexible sensor 60. The electrical connections may be formed as apermanent and/or semi-permanent electrical connection, using solder, aconductive epoxy, screw terminals, spring terminals, a compressionfitting, a snap fitting, a crimp fitting, or the like. The electricalconnections may be accessible to a user with or without disassembly ofat least a portion (e.g., a cover) of the wear state monitor 50. Forexample, a user may be capable of accessing a terminal via the opening225 and/or by removing a removable cover that may comprise an end 201,203 of the wear state monitor 50. The cover may be secured by a threadedconnection, a snap-fit connection and/or one or more connectors (e.g.,screws). In some cases, the exterior housing of the wear state monitor50 may be configured in two or more sections that may be hingedlyconnected (e.g., a “clam shell” configuration), or otherwise movablerelative to one another. In such cases, when the wear state monitor 50is located within the coiled portion of the spring 29 (e.g., a helicalspring), the force provided by the spring 29 may facilitate acompression connection or snap fit connection for the hingedly connectedsections of the housing of the wear state monitor 50. Also, the forceprovided by the spring 29 may also facilitate a compression connectionor other pressure based electrical connection between the wear statemonitor 50 and the flexible sensor 60. In some cases, the flexiblesensor 60 may be electrically connected to the wear state monitor usingan interface (e.g., one or more terminals, one or more bonding pads,etc.) located at an end 201, 203 and/or on the body 210 of the wearstate monitor 50. In some cases, an externally accessible electricalconnection interface for the flexible sensor 60 may extend above thesurface of the wear state monitor 50, or may be recessed in a cavityformed into the exterior surface of one or more of the ends 201, 203 orthe body 210.

The wear state monitor 50 may be capable of communicating informationabout the wear state of the brush 24 and/or the rotating component 15 toa user via the communication interface 230 and/or the indicators 240.The communication interface 230 and/or the indicators 240 may be locatedat the same or different surface of the wear state monitor 50. Forexample, the communication interface 230 may be located at a first end201 of the wear sensor and the indicators 240 may be located at a secondend 203 of the wear state monitor, but this is not required. Thecommunication interface 230 may be capable of transmitting informationvia one or more communication protocols using audio energy (e.g. anultrasonic signal), radio frequency (RF) energy (e.g., an RF signal),and/or light energy (e.g., an optical signal, an infrared (IR) signal,etc.), or the like.

In some cases, the wear state monitor 50 may be capable of receivingmessages from an external device, such as the site monitor 120 and/or aprogramming device located at the same site or at a remote location(e.g., a computer 150, a tablet 160, a smart phone, etc.). The messagesmay include commands, such as commands to send wear state informationabout the brush 24 and/or the rotating component 15, or commands formodifying information used by the wear state monitor 50. For example, auser may desire to modify one or more thresholds used to determine thewear state information of the brush 24 and/or the rotating component 15,and/or to reprogram the wear state monitor 50 by downloadinginstructions, tables and/or the like (e.g., compiled code). In somecases, the wear state monitor 50 may include one or more user interfaces260 that may be used for programming or otherwise providing informationabout the location and/or function of the wear state monitor 50. Forexample, a user may use the user interface 260 as a programminginterface to modify one or more thresholds and/or to reprogram the wearstate monitor 50 rather than using the communication interface 230. Forexample, a user may connect a programming device via a cable or use oneor more memory devices (e.g., a flash card, a universal serial bus (USB)drive, etc.) to download and/or upload information from the wear statemonitor 50. In some cases, the user interface 260 may include one ormore switches (e.g. a dual inline package (DIP) switch, a rotaryposition switch, etc.) to associate the wear state monitor 50 with aparticular brush assembly 110 and/or a particular installed position atthe electrical machine and/or at the customer site.

The indicators 240 may include one or more optical indicators (e.g.LEDs) and/or one or more audio indicators (e.g., a speaker) forproviding an optical and/or audible indication of the wear state of thebrush 24 and/or the wear state of the rotating component 15. Forexample, indicators 240 of the wear state monitor 50 may include one ormore LEDs, wherein the one or more light emitting diodes (LED) may beconfigured to emit light of a first color when the wear state monitor 50determines a first wear state of the brush 24 and to emit light of asecond color when the wear state monitor 50 determines a second wearstate of the brush 24. In some cases, additional colors may be used toindicate additional wear states of the brush 24. The indicators may usethe same and/or different ones of the one or more LEDs to indicate thewear state information of the rotating component 15. For example, theone or more LEDs may be configured to emit light of a third color whenthe wear state monitor 50 determines a first wear state of the rotatingcomponent 15 and to emit light of a fourth color when the wear statemonitor 50 determines a second wear state of the of the rotatingcomponent 15. In some cases, additional colors may be used to indicateadditional wear states of the rotating component 15. In some cases, afirst set of LEDs may be configured to provide wear state informationabout the brush 24 and a second set of LEDs for indicating wear stateinformation about the rotating component 15

For example, the wear state monitor 50 may include one or more LEDsconfigured to emit light of a first color (e.g., green) when the wearstate monitor 50 determines that the brush 24 has an operational wearstate, to emit light of a second color (e.g., yellow) when the wearstate monitor 50 determines that the brush 24 is approaching thereplacement wear state, and to emit light of a third color (e.g., red)when the wear state monitor 50 determines that the brush 24 has reachedthe replacement wear state. In some cases, the wear state monitor 50 maybe configured to illuminate a different number of LEDs and/or a patternof LEDs, of the same or different colors, to indicate one or moreparticular wear state conditions of the brush 24 and/or the rotatingcomponent 15.

In another example, the wear state monitor 50 may be configured toprovide a first audible indication of the wear state of the brush 24(e.g., an intermittent tone) when the wear state monitor 50 determinesthat the brush 24 is approaching the replacement wear state, and toprovide a second audible indication of the wear state of the brush 24(e.g., a different intermittent tone, a tone at a different frequency, asteady tone, etc.) when the wear state monitor 50 determines that thebrush 24 has reached the replacement wear state.

FIG. 3 shows an exploded perspective view of the brush holder assembly110 in an engaged position and including the illustrative wear statemonitor 50 of FIGS. 1 and 2. In some cases, the brush holder assembly110 may include an integral flexible sensor 60 that may be used formonitoring a wear state of the brush 24 and/or an associated rotatingcomponent 15 of an electrical machine. The brush holder assembly 110 mayinclude the brush 24 (e.g. a carbon brush) and a spring 29 associatedwith the brush 24. The spring 29 may provide a force to engage the brush24 with a rotating component of an electrical machine, such as a slipring, a commutator, and the like. For example, the spring 29 may includea coil portion 310 that may be used to apply the force to the brush 24.The wear state monitor 50 may be positioned adjacent to the spring 29.In some cases, the wear state monitor 50 may be positioned substantiallywithin the coil 310.

In some cases, the flexible sensor 60 may be positioned adjacent to thespring 29 such that the changing bend radius of the spring 29 associatedwith the movement and/or wear of the brush 24 causes a correspondingbend radius on the flexible sensor 60. For example, the flexible sensor60 may be affixed or otherwise positioned adjacent to a surface of thespring 29. In another example, the flexible sensor 60 may be positionedadjacent to an edge of the spring 29.

Other configurations for positioning the flexible sensor 60 in relationto the spring 29 and/or brush 25 may be contemplated. For example, aportion of the flexible sensor 60 may be affixed to one or more othercomponents of the brush holder assembly 110 (e.g., the brush holder 22,the handle 21, the upper beam member 27, the lower beam member 28, andthe like). In such cases, a different portion of the flexible sensor 60may be communicatively coupled to the wear state monitor 50 located inthe coil portion 310 of the spring 29 or other location of the brushholder assembly 110. In some cases, the flexible sensor 60 may have afirst bend radius upon initial installation of the brush 24 that is lessthan the bend radius after the brush 24 is worn. In other cases, theflexible sensor 60 may have a first bend radius upon initialinstallation that is greater than the bend radius after the brush 24 isworn. In some instances, the flexible sensor 60 may have a configurationsuch that the bend sensor 60 does not have a bend radius, such as whenthe bend sensor 60 is substantially aligned along a plane. For example,the bend radius of the flexible sensor 60 may have a positive bendradius upon installation and a negative bend radius after the brush isworn, or a negative bend radius upon installation and a positive bendradius after the brush is worn, or the bend sensor may be substantiallyaligned along a plane at initial installation or after a particularamount of wear to the brush 24. In some cases, two or more flexiblesensors 60 may be used for monitoring the wear states of the brush 24and/or the rotating component 15. The two or more flexible sensors 60may be positioned adjacent to different portions of the spring, suchthat a first flexible sensor 60 may be used to monitor the wear state ofthe brush 24 and/or the rotating component 15 over a first duration oftime and a second flexible sensor 60 may be used to monitor the wearstate of the brush 24 and/or the rotating component 15 over a secondduration of time. The first and second durations of time may overlap insome instances. In an illustrative example, the first flexible sensor 60may be at least partially bent (e.g., positioned near the coil of thespring 29) and the second flexible sensor 60 may be significantlystraight (e.g., positioned near the lower beam member 28), such that thewear state monitor 50 may be configured to primarily or solely useinformation from the first flexible sensor 60 during a duration of timeafter installation of the brush assembly 110 on the machine, acombination of information received from both the first and secondflexible sensors during a second duration of time during normaloperation, and information received primarily or solely from the secondflexible sensor at a third duration of time, such as a duration of timewhen the brush 24 is approaching a replacement wear state or isotherwise near a replacement wear state. In some cases, a sensor otherthan a flexible sensor having a variable resistance may be contemplatedto obtain information about an amount of wear to the brush 24 and/or anamount of wear to the rotating component 15 in relation to a movement ofthe spring 29. Obtaining information about an amount of wear to therotating component 15 includes obtaining information about an amount ofwear to the surface 12 of the rotating component 15. In some cases, oneor more wires may be positioned adjacent to the spring 24. For example,a portion of one or more wires may be affixed to the spring 24. In somecases, an opening in a portion of an insulating layer around the one ormore wires may be present to expose a portion of the wire. In suchcases, the exposed and/or un-insulated portion of the wire may contactanother surface (e.g., a surface of the spring 29, a surface of thebrush 24, or another surface associated with the brush assembly 110),which may cause the wire to conduct electricity and/or stop conductingelectricity. In some cases a first wire may be positioned to indicate aknown wear state of the brush 24, such as an initial wear statecondition, a wear state approaching a replacement wear state conditionof the brush 24, and/or a replacement wear state condition of the brush24. In some cases, a second or additional wire may be positioned toindicate another wear state of the brush 24 different from the firstwear state. For example, a first wire may be used to indicate a wearstate approaching a replacement wear state, and a second wire may beused to indicate a replacement wear state of the brush 24. In somecases, the wire may be associated with one or more resistors, and/orother electrical components. In such cases, as the wear state of thebrush 24 changes, different ones of the one or more electricalcomponents (e.g., transistors, LEDs, resistors, etc.) may be included inan electrical circuit. For example, a first resistance value may beassociated with a first particular wear state and a second resistancevalue may be associated with a second particular wear state. In somecases, the wear state monitor 50 may include a sensor or other device toat least partially identify a vibration or other movement correspondingto a wear state of the rotating component 15. For example, anacceleration and/or a pressure sensor may be associated with the wearstate monitor 50 and information received from the acceleration and/orthe pressure sensor may be used to identify a characteristic (e.g., amagnitude, a frequency, etc.) of a vibration of the brush 24. The wearstate monitor 50 may use this information in addition to or in place ofinformation received from the flexible sensor 60, such as a bend sensor,or other sensor (e.g., a temperature sensor, a humidity sensor, etc.) todetermine whether the wear state of the rotating component 15 isapproaching a maintenance wear state or has reached a requiredmaintenance wear state.

The wear state monitor 50 may be communicatively coupled to the flexiblesensor 60 to receive a signal corresponding to the wear state of atleast one of the brush 24 and the rotating component 15. The wear statemonitor 50 may be configured to determine the wear state of the brush 24and/or the rotating component 15 using a comparator by comparing thesignal received from the flexible sensor 60 to at least onepredetermined threshold. The wear state monitor 50 may provide thedetermined wear state information about the brush 24 and/or the rotatingcomponent 15 to a user via an indicator provided on the wear statemonitor 50 and/or a communication circuit capable of communicating to anexternal device, such as the site monitor 120, via a communication link.

FIG. 4 is a block diagram representation of the illustrative wear statemonitor 50 of FIGS. 1-3. In an example, the illustrative wear statemonitor 50 may be communicatively coupled to a sensor, such as theflexible sensor 60 to obtain information about the wear state of thebrush 24 and/or the rotating component of the electrical machine. Inthis illustrative embodiment, the wear state monitor 50 may include oneor more of an input/output block (I/O block) 410, a signal conditioningcircuit 420, a comparison circuit 430 (e.g., a comparator), a processor440 (e.g. a microprocessor, a microcontroller, etc.), a user interface450, a communication circuit 470, a memory 480 and/or a data port 490.In some cases, the wear state monitor 50 may include a power source 460,such as a battery, a capacitor, or both. In some cases, the battery maybe rechargeable and/or replaceable. In some cases, the wear statemonitor 50 may include energy harvesting capability, such that the powersource 460 may receive energy and/or may be recharged by one or moreenergy harvesting technologies. For example, illustrative energyharvesting technologies may include a kinetic (e.g., vibrational) energyharvester (e.g., a piezoelectric vibration energy harvester, amagneto-inductive vibration energy harvester, etc.), a photovoltaicenergy harvester capable of harvesting energy indoors and/or outdoors, apiezoelectric energy harvester, a thermal energy harvester, a windenergy (e.g., microturbine) harvester, and/or an ambient radiation (e.g.radio frequency) energy harvester.

In some cases, in addition to or instead of the power source 460, thewear state monitor 50 may include one or more connectors and/orterminals capable of receiving power from a source separate from thewear state monitor 50. In such cases, the wear state monitor 50 may beconfigured to receive power from an external power source when the brushholder assembly 110 is installed on the electrical machine. For example,an electrical circuit to the wear state monitor 50 may be completed whenthe brush holder assembly 110 is coupled to the mounting block 70 suchthat electrical power may pass from a power source through the mountingblock 70 to the wear state monitor 50. In such a configuration,electrical power may be automatically provided to the wear state monitor50 when the brush holder assembly 110 is mounted onto the mounting block70 of the electrical machine, and electrical power to the wear statemonitor 50 may be discontinued when the brush holder assembly 110 isremoved from the mounting block 70. In some cases, the I/O block 410 mayinclude one or more connectors 415 (e.g., screw terminals, springterminals, etc.) for connecting the flexible sensor 60 to the wear statemonitor 50. In some cases, the I/O block 410 may be located within thewear state monitor 50 or may be positioned on or near an externalsurface of the wear state monitor 50. For example, the I/O block 410 maybe positioned within a cavity within the wear state monitor 50 andaccessible via an opening and/or a removable cover. A signal receivedfrom the flexible sensor 60 may be conditioned by the signalconditioning circuit 420.

The signal conditioning circuit 420 may be configured to performfiltering, amplification, buffering, and/or other adjustments to theamplified pressure indicating signal. In some cases, the signalconditioning circuit 420 may include one or more discrete components(e.g., resistors, transistors, capacitors, inductors, diodes, etc.)and/or integrated circuits (e.g., operational amplifiers, buffers,ASICs, etc.). In some cases, the signal conditioning circuit 420 mayinclude one or more filters 422. The filters 422 may be implemented as acombination of integrated or discrete elements, such as a resistor and acapacitor configured as a series RC network (e.g., a low-pass filter).Although a first order low-pass filter may be used, it is contemplatedthat any combination of analog or digital filters can be used, includingone or more high pass filters, low pass filters, band pass filters,notch filters, passive filters (e.g., having “T” sections, “π” sections,etc.), active filters (e.g., Chebyshev filter, Butterworth filter,etc.), IIR filters, FIR filters, and/or any other suitable filter orfilter combination.

The signal received from the flexible sensor 60 may then be compared toone or more predetermined thresholds using the comparison circuit 430.In some cases, the threshold for the one or more thresholds may be setusing one or more discrete electrical components, such as one or moreresistors, capacitors, inductors, diodes, transistors, and/or integratedcircuits, such as a comparator and/or a processor. In some cases, theprocessor 440 may read the threshold from a memory 480 and/or computethe threshold using one or more instructions stored in the memory 480.In some cases, the specified threshold may be fixed at a pre-determinedlevel. In other cases, the specified threshold may be configurableand/or adaptable, as desired. For example, the one or more thresholdsmay be configurable by a user during a calibration procedure beforeand/or after the wear state monitor 50 is installed in a brush holderassembly 110. During an illustrative calibration procedure, the user mayobtain one or more steady-state values from the flexible sensor 60 afterthe flexible sensor 60 is installed in the brush holder assembly 110.For example, the obtained values may correspond to a first position ofthe brush 24, such as an engaged position when the brush 24 hasapproximately no wear and a second position corresponding to a brushposition approximating a position when the brush 24 has a predeterminedamount of wear (e.g., approaching the replacement threshold, maximumallowable wear, etc.). Calibration may be important due to one or moremechanical and/or electrical differences between particular brushassemblies. In some cases, a user may communicate a threshold value viaa communication interface, such as the communication circuit 470, theuser interface 450 (e.g., using one or more switches 454 and/orpotentiometers 458), and or the data port 490, such as from an externalmemory device (e.g., a flash memory device, etc.).

The processor 440 may operate using an algorithm for determining a wearstate indication of at least one of the brush 24 and the rotatingcomponent 15 and/or communicates one or more indication of the wearstate of the brush 24 and/or rotating component 15 to a user. Theprocessor 440 may, for example, operate using an algorithm that causesthe wear state monitor 50 to obtain information corresponding to a bendradius of the flexible sensor 60 continuously or at predeterminedintervals. In some cases, wear state monitor 50 may include a timer 445and/or an analog to digital converter (ADC) 447. The timer 445 and/orthe ADC 447 may be integral to the processor 440 or may be provided as aseparate component. In some cases, one or more components and/orfunctionality of the signal conditioning circuit 420 and/or thecomparison circuit 430 may be incorporated into the instructionsprocessed by the processor 440.

The memory 480 of the illustrative wear state monitor 50 may be incommunication with the processor 440. The memory 480 may be used tostore any desired information, such as the aforementioned controlalgorithm, threshold values, schedule times, sampling times, trendinginformation, and the like. The memory 480 may be any suitable type ofstorage device including, but not limited to, RAM, ROM, EPROM, flashmemory, a hard drive, and/or the like. In some cases, the processor 440may store information within the memory 480, and may subsequentlyretrieve the stored information.

In the illustrative embodiment of FIG. 4, the user interface 450 may beany suitable user interface that permits the wear state monitor 50 todisplay and/or solicit information. In some cases, the user interface450 may accept one or more user interactions with the wear state monitor50 and/or may permit the wear state monitor 50 to display, or otherwiseconvey, information about the wear state of the brush 24 and/or therotating component 15. For example, the user interface 450 may includeone or more indicators, such as LEDs 452 or speakers 456, capable ofproviding the indication of the determined wear states to the user. TheLEDs 452 may include one or more LEDs 452 capable of emitting one ormore colors, the colors and/or the lack of colors being representativeof a corresponding wear state. For example, an unlit LED and/or an LEDemitting a green light (optional) may indicate an operational or “good”wear state, an LED emitting a yellow light may indicate a wear statewhere the associated component may be approaching a replacement wearstate, and an LED emitting a red light may indicate a replacement wearstate. The listed color choices are merely representative and othercolors and/or combinations of colors may be contemplated. In some cases,the user interface 450 may be configured to illuminate a differentnumber of LEDs 452 and/or a pattern of LEDs 452 to indicate one or moreparticular wear state conditions of the brush 24 and/or the rotatingcomponent 15. In some cases, a reflective surface (e.g., the polishedbrush box of the brush holder 22, a separate reflector, etc.) may beused to direct and/or amplify light emitted by the one or more LEDs.

In some cases, the wear state of the brush 24 and/or rotating component15 may be indicated by the user interface 450 via the speaker 456. Thespeaker 456 may be used to emit an audible indication, such as aspecified tone for a specified duration, for one or more wear states ofthe brush 24 and/or the rotating component 15.

In some cases, the user interface 450 may include one or more componentsto allow a user to input information about the wear state monitor 50(e.g., a communication address, an installed location, etc.),information about the flexible sensor 60 and/or brush holder assembly110 (e.g., calibration information, threshold information, etc.), orother information about the brush monitoring system 100. For example,the user interface 450 may include one or more switches 454 that may beused to assign a communication address or other identificationinformation, to a particular wear state monitor 50, assign acommunication channel and/or frequency for communication via thecommunication link 115, specifying a monitoring schedule, and/or adjusta threshold by, for example, adding and/or removing a resistor networkto adjust a voltage divider network. For example, a user interface 450may include one or more groups of switches 454, where a first portion ofswitches 454 may be used to assign a site address, a second portion ofthe switches 454 may be used to assign an electrical machine number anda third portion of the switches 454 may be used to assign a brushassembly number or identify a location of the brush assembly 110. Insome cases, the user interface 450 may include one or morepotentiometers and/or variable resistors that may be used to adjust athreshold, such as during a configuration process. These user interfacecomponents are merely illustrative and other components may becontemplated.

In some cases, user interface 450 may include a display 458 and one ormore buttons 459 for entering information, such as by navigating one ormore menu options. The display 458 may be any suitable display. In someinstances, a display 458 may include or may be a liquid crystal display(LCD), and in some cases a fixed segment display or a dot matrix LCDdisplay. If desired, user interface 450 may be a touch screen LCD panelthat may operate both display 458 and data entry functions. In someinstances, the display 458 may be adapted to solicit values for a numberof operating parameters and/or to receive such values, but this is notrequired. In some cases, the user may be capable of entering at least aportion of the identification information (e.g., a site number, amachine number, a brush assembly number) using the touch screen display,the keyboard, the buttons 459 or other means of inputting the numericaland/or textual information

In many cases, when a diagnostic limit, such as a predeterminedthreshold, has been violated, the processor 440 may be configured toindicate to the user that a diagnostic fault has occurred. This may beaccomplished in any of a variety of ways. For example, if the processor440 has determined that a diagnostic limit has been violated, and adiagnostic fault has occurred, the processor 440 may cause a user alertto be indicated by the user interface 450. In some cases, the processor440 may process instructions to alert the user to a particular wearstate only after a predetermined number of threshold violations and/orthat a threshold violation exceeds a particular duration are detected bythe processor 440. For example, the processor 440 may be programmed toindicate a wear state of the brush 24 after a particular threshold valuehas been met for at least a predetermined threshold (e.g., 5 seconds, 30seconds, 1 minute, etc.). Similarly, the processor 440 may be programmedto indicate a wear state of the rotating component 15 after a particularthreshold (e.g., a replacement threshold) has been exceeded for aspecified number of times (e.g., ten times, fifteen times, etc.) withina particular duration (e.g., 30 seconds, 1 minute, etc.) and/or aspecified number of revolutions of the rotating component (e.g., 10revolutions, 20 revolutions, etc.). In some cases, the user alert may bean audible tone from the speaker 456 and/or a simple text stringdisplayed on a display of the user interface 450 which may describe thenature of the violation that has occurred. In other instances, theprocessor 440 may provide some visual indication to alert the user thata fault has occurred. Such visual indication may include a colored,flashing or otherwise visible indication provided on the user interface450. In still other instances, the processor 440 may be configured toprovide information to another device, such as the site monitor 120 orthe remote monitoring device 150, 160. One or more of the site monitor120 or the remote monitoring device 150, 160 may provide the informationto a user via a visual indication, an audible indication, an email, aninstant message, a text message or some other message to a user to alertthe user of the wear state of the one or more components of the brushholder assembly 110. Such information may be provided via an internetgateway 170 or other device that is adapted to communicate over theinternet or other wide area network, a local area network, and the like.For example, the internet gateway 170 may be configured to communicatewith the network 130, and/or an industrial control system. Such an alertmay be provided to the user even when the user is away from the site inwhich the brush monitoring system 100 is located.

In addition to the user interface 450, the wear state monitor 50 may becapable of communicating information about the wear state of the brush24 and/or the rotating component 15 to a user via the communicationcircuit 470. The information about the wear state of the brush 24 and/orthe rotating component 15 may be associated with information identifyingone or more of a particular site, a particular electrical machine and/ora particular brush assembly associated with the brush 24 and/or therotating component 15. In some cases, the communication circuit 470 mayinclude a communication port (e.g., a speaker 472, a transceiver 474,etc.) that may be used to communicate with the site monitor 120 via thecommunication link 115. One or more communication protocols may be usedby the wear state monitor 50 to communicate wear state informationassociated with the brush holder assembly 110 to the site monitor 120.The communication circuit 470 may include a chipset capable ofcommunicating via one or more communication link technologies such as byusing audio energy (e.g. an ultrasonic signal), radio frequency (RF)energy (e.g., an RF signal), and/or light energy (e.g., an opticalsignal, an infrared (IR) signal, etc.), or the like. In some cases, thecommunication circuit 470 may be capable of communicating via one ormore other wireless technologies such as Bluetooth™, Wi-Fi, Zigbee orany other wireless protocol. In some cases, the communication circuit470 may be configured to communicate via one or more wired interfaces,but this is not required. For example, the communication circuit 470 mayinclude a wired port such as a serial port, an ARCNET port, a parallelport, a serial port, a CATS port, a USB (universal serial bus) port,and/or the like. In some cases, the communication circuit 470 may useone or more communication protocols, such as Ethernet, BACNet, LONtalk,DeviceNet, ControlNet, Profibus, etc., that may be used via a wirednetwork or a wireless network.

In some cases, as illustrated in FIG. 4, the wear state monitor 50 mayoptionally include a data port 490. Data port 490 may be a wireless portsuch as a Bluetooth™ port or any other wireless protocol. In othercases, data port 490 may be a wired port such as a serial port, aparallel port, a CATS port, a USB (universal serial bus) port, and/orthe like. In some instances, data port 490 may be a USB port and may beused to download and/or upload information from a USB flash drive orsome other data source. Other remote devices may also be employed, asdesired. The data port 490 may be configured to communicate withprocessor 440 and may, if desired, be used to upload information toprocessor 440 and/or download information from the processor 440.Information that can be uploaded and/or downloaded may include, forexample, values of thresholds and/or timing information. In someinstances, the data port 490 may be used to upload previously-createdconfiguration information of the wear state monitor 50 and/or theflexible sensor 60, thereby hastening the configuration process. In somecases, data port 490 may be used to download a configuration that hasbeen created using a particular wear state monitor 50 and/or flexiblesensor 60 so that the configuration may be transferred to other similarwear state monitors 50, hastening their programming process. In somecases, the data port 490 may be used to upload and/or downloadinformation pertaining to wear state trends of the brush 24 and/or therotating component 15, if desired.

In some cases, data port 490 may be used to download data stored withinthe memory 480 for analysis. For example, data port 490 may be used todownload a wear state log associated with the brush 24 and/or therotating component or parts thereof to a removable device such as a USBmemory stick (also sometimes referred to as a thumb drive or jumpdrive), personal computer, laptop, iPAD® or other tablet computer, PDA,smart phone, or other remote device, as desired. In some cases, the datamay be convertible to an MS EXCEL®, MS WORD®, text, XML, and/or AdobePDF® file, but this is certainly not required.

In some cases, the wear state monitor 50 may include one or moreenvironmental sensors capable of sensing characteristics of theenvironment near the brush holder assembly 110. Examples of theenvironmental sensors may include a temperature sensor and/or a humiditysensor. The wear state monitor 50 may be configured to use the sensedenvironmental information when determining a threshold and/or maycommunicate the sensed environmental information to another device, suchas the site monitor 120 or the remote monitoring device 150, 160.

FIGS. 5A and 5B are perspective views of an illustrative flexible sensor60 of FIGS. 1, 3, and 4. The illustrative flexible sensor 60 may includea substrate 510, at least one ink layer 520, and two or more electricalconnectors 530 that may be connected to one or more wires 540. Theflexible sensor 60 may be substantially flat and may be selected from avariety of lengths, widths and/or thicknesses. In some cases, theflexible sensor 60 may have a variable resistance that is designed tochange as the flexible sensor 60 is bent. The flexible sensor 60 may beformed by depositing the one or more electrically conductive ink layers520 onto a top surface 515 of the substrate 510. For example, thesubstrate 510 may be formed from a flexible, electrically insulatingmaterial, such as a plastic film (e.g., a biaxially-orientedpolyethylene terephthalate film, a polyimide film, a polyester film, apolyamide film, a phenolic resin etc.). The electrically conductive inklayers 520 may be adhered to the top surface 515 of the substrate 510and may be formed from one or more electrically conductive inks (e.g., acarbon-based ink, a polymer based ink, a composite ink, and the like)and/or one or more other electrically conductive materials, such as anepoxy and/or an adhesive where the epoxy or adhesive includes aconductive material (e.g., graphite, carbon, etc.). In some cases, theelectrically conductive ink layers 520 may be capable of formingmicro-cracks as the substrate 510 is bent, where the size and or shapeof the micro-cracks causes the electrical resistance of the flexiblesensor 60 to change in a predictable manner. Examples of such a flexiblesensor 60 may include the Bend Sensor® from Flexpoint Sensor Systems,Inc. of Draper Utah. Other examples of flexible sensors are disclosed inU.S. Pat. Nos. 7,248,142; 8,047,083; 7,277,004; and 5,157,372; each ofwhich is incorporated herein by reference.

As discussed above, the flexible sensor 60 may have a variableresistance that is designed to change as the flexible sensor 60 is bent.The flexible sensor 60 may be connected to a wear state monitor 50 by anelectrical connection, such as one or more terminals 530, wires 540 orother such means to form an electrical connection. In some cases, thewires 540 may be shielded to reduce an amount electrical noiseintroduced into the circuitry of the wear state monitor 50 from thebrush monitoring system 100. For example, the wires 540 may be a twistedpair of wires 540 included in a cable having a shield 550. In somecases, such as in FIG. 5B, the electrical connectors 530 may beconnected directly to one or more terminals 425 of the wear statemonitor 50.

The power source 460 (e.g., a battery) of the wear state monitor 50 maybe used to supply power to one or more components of the wear statemonitor 50 and/or the flexible sensor 60 to facilitate generation of asignal representative of a bending radius of the flexible sensor 60. Forexample, the wear state monitor 50 and the flexible sensor 60 mayoperate together to form at least a portion of a voltage divider circuitto produce a voltage output that is a fraction of a power sourcevoltage. By bending the flexible sensor 60 using a bending force, suchas the force provided by the spring 29 to maintain physical contactbetween the brush 24 and the surface of the rotating component 15, thebending force may cause a change in resistance of the flexible sensor60. The change in the resistance of the flexible sensor 60 maycorrespond to the physical position of a top surface 624 of the brush 24in relation to the conductive surface 12 of the rotating component 15.The variable resistance of the flexible sensor 60 may vary linearly ornon-linearly corresponding to a degree of bending of the flexible sensor60. Similarly, the change in resistance of the flexible sensor 60 causesa corresponding change in the voltage output of the signalrepresentative of the bend radius of the flexible sensor 60.

Information about the bend radius of the flexible sensor 60 may be usedto determine a wear state of the brush 24 and/or the condition of arotating component 15 of the electrical machine (e.g., a slip ring). Asmentioned above, the wear state monitor 50 may be electrically connectedto the flexible sensor 60 by the wires 540. The wear state monitor 50may determine a wear state of the brush 24 and/or the rotating component15 by comparing at least a portion of the signal representative of thebend radius of the flexible sensor 60 to one or more predeterminedthreshold values. In some cases, the wear state monitor 50 may beconfigured to include a first threshold value corresponding to a firstwear state of the brush 24 and a second threshold value different fromthe first threshold value corresponding to a second wear state of thebrush 24. For example, the first threshold value may be a first voltagelevel associated with a brush wear state indicative of a wear statewhere the brush 24 should be replaced within a predetermined time period(e.g., within a week). The second threshold value may correspond to awear state of the brush 24 indicative of a wear state requiring thebrush 24 to be replaced as soon as possible.

In some cases, the wear state monitor 50 may be configured to monitor avibration of the brush 24. For example, a vibration of a brush 24 may bedue to one or more imperfections or other deformation of the rotatingcomponent 15 of the electrical machine. For example, a slip ring maydeform or may wear unevenly to cause one or more portions of the slipring to be out of round. As the brush 24 encounters these defects at oneor more positions during a revolution of the rotating component 15, thedefects may cause the brush 24 to vibrate at a rate corresponding to therotation speed and/or the number of defects at the conductive surface 12of the rotating component 15 (e.g., a slip ring, a commutator, etc.). Insome cases, the wear state monitor 50 may be configured to include athird threshold value, different than the first and second thresholdvalues, corresponding to a first wear condition of the rotatingcomponent 15 of the electrical machine and a fourth threshold value,different than the first, second and third threshold values,corresponding to a second wear condition of the rotating component 15.For example, the third threshold value may be a first voltage levelassociated with a condition of the rotating component 15 indicative of awear state where the rotating component 15 should be replaced and/orrepaired within a predetermined time period (e.g., within a week). Thefourth threshold value may correspond to a condition of the rotatingcomponent 15 indicative of a condition where maintenance (e.g.,replacement and/or repair) of the rotating component 15 should becompleted as soon as possible.

FIGS. 6A and 6B show perspective views of an illustrative brush holderassembly 600, such as the brush holder assembly 110 of FIG. 1, atdifferent identifiable wear states of the brush 24. The wear statemonitor 50 may be positioned within the coil 310 of the spring 29. Theflexible sensor 60 may be positioned adjacent to the spring 29 andelectrically connected to the wear state monitor 50. Here, thiselectrical connection is not shown to simplify the illustration. FIG. 6Aillustrates a first wear state of the brush 24, such as an initial wearstate of the brush 24 when the brush holder assembly 600 is firstinstalled on an electrical machine. For example, when the brush holderassembly 600 is in an engaged position, the spring 29 applies a force tothe top surface 624 of the brush 24 to engage the brush 24 with theconductive surface 12 of the rotating component 15. The top surface 624may be at a first position where the bending force of the spring 29causes a first bend radius 610. The first bend radius 610 may cause theflexible sensor 60 to have a first resistance value that may beassociated with the initial wear state of the brush 24. A second bendradius 640 may cause the flexible sensor 60 to have a second differentresistance value that may be associated with a different wear state ofthe brush 24, such as a wear state approaching a replacement wear stateor a replacement wear state. The brush monitoring system 100 and/orcomponents of the brush monitoring system (e.g., the wear state monitor50, the site monitor 120, the remote monitoring devices 150, 160) may becalibrated to account for variations in geometry of the brush holderassembly and/or the brush, the differing forces applied by differentsprings, and/or for other factors that may change between differentbrush holder assemblies 110. In some cases, the wear state monitor 50may be resiliently mounted within the coil of the brush 24, such thatvibrations of the brush 24 may be absorbed and/or dampened.

The resistance value of the flexible sensor 60 at the different bendradiuses may be caused by a series of microcracks 665 formed within theink layer 520 that may form as the flexible sensor 60 bends. Themicro-cracks 665 may form due to cracking of a brittle component of theink layer 520, while a flexible component may maintain the overallintegrity of the ink layer 520. The micro-cracks 665 in the ink layer520 cause the electrical resistance of the flexible sensor 60 to change.As a bend radius decreases due to the applied bending force, moremicro-cracks 665 form in the ink layer 520 causing the resistance of theflexible sensor 60 to increase. The resistance can vary based on themagnitude of bending force applied to the flexible sensor 60, the amountof wear of the brush 24 and/or the movement of the brush 24. The wearstate monitor 50 may receive a variable voltage signal from the flexiblesensor 60 based on the variable resistance of the flexible sensor 60 dueto movement over a duration of interest. A smaller radius of curvaturemay correspond to a larger resistance value of the flexible sensor 60.For example, the electrical resistance of the flexible sensor 60 at thefirst bend radius 610 is less than the electrical resistance of theflexible sensor 60 at the second bend radius 640. The flexible sensor 60may be repeatedly bent because the ink layer 520 continues to have astrong bond to the substrate 510. The resistance of the flexible sensor60 returns to the first resistance value when the flexible sensor 60returns to the first bend radius 610.

The flexible sensor 60 may be installed within the brush holder assembly110 such that a proximal end 661 including the electrical connections,such as terminals 530, may be oriented toward the wear state monitor 50and a distal end 661 may be oriented away from the wear state monitor50. In the example of FIG. 6A, at the initial wear state of the brush24, at least a portion of the flexible sensor 60 including the distalend is oriented along a first plane 620 and another portion of theflexible sensor including the proximal end is oriented along a secondplane 630, where the deflection 615 between the first plane 620 and thesecond plane 630 corresponds to the first bend radius 610. In FIG. 6B,the brush 24 is shown at a second wear state such that the top surface624 is at a different second position 651 at a deflection distance 655from the initial wear state position 605. At this second position 651,at least a portion of the flexible sensor 60 including the distal end661 is now oriented along a third plane 650 and another portion of theflexible sensor 60 including the proximal end 662 is oriented along athird plane 650, where the deflection 645 between the third plane 650and the second plane 630 corresponds to the second bend radius 640.

FIG. 7 is a block diagram representation of a brush monitoring system700 having an illustrative site monitor 720, such as the site monitor120. At a facility, one or more electrical machines 710 may beconfigured to include one or more brush holder assemblies 715, such asthe brush holder assembly 110. The brush holder assemblies 715 may bepositioned around a rotating portion 730 (e.g. a shaft) of an electricalmachine (e.g., a motor, a generator, etc.). The brush holder assemblies715 may be positioned such that a brush 24 contacts a surface of arotating component (e.g., a slip ring, a commutator) associated with therotating portion 730 of the electrical machine. In some cases, the brushholder assemblies 715 may be mounted to a portion of the electricalmachine using one or more adapters 726 that include the mounting beam 26of FIGS. 1 and 3. Each of the brush holder assemblies 715 may beconfigured to communicate to the site monitor 720 via a communicationlink 115.

The site monitor 720 may include a communication circuit 740, aprocessor 750, a memory 760, an I/O block 770, a data port 780, a userinterface 790, and/or one or more sensors 795. In some cases, thecommunication circuit 740 may include a signal conditioning circuit 741that may be used to filter and/or otherwise condition the signalreceived from the one or more brush holder assemblies 715. The sitemonitor 720 may include a power source 792, such as a battery, acapacitor, and/or a power line adapter. In some cases, the battery maybe rechargeable and/or replaceable. In some cases, the site monitor 720may include an energy harvesting capability, such that the power source792 may receive energy and/or may be recharged by one or more energyharvesting technologies. For example, illustrative energy harvestingtechnologies may include a kinetic (e.g., vibrational) energy harvester(e.g., a piezoelectric vibration energy harvester, a magneto-inductivevibration energy harvester, etc.), a photovoltaic energy harvestercapable of harvesting energy indoors and/or outdoors, a piezoelectricenergy harvester, a thermal energy harvester, a wind energy (e.g.,microturbine) harvester, and/or an ambient radiation (e.g. radiofrequency) energy harvester.

The communication circuit 740 may be capable of receiving informationabout the wear state of the brush 24 and/or the rotating component (e.g.a slip ring, a commutator, etc.) associated with the rotating portion730 of the electrical machine from one or more wear state monitors(e.g., the wear state monitor 50) associated with the brush holderassemblies 715 and/or communicating configuration and/or timinginformation to the one or more wear state monitors 50. In some cases,the communication circuit 740 may include a communication port (e.g., anaudio receiver/transmitter 742, an RF transceiver 744, etc.) that may beused to communicate with the wear state monitor 50 via the communicationlink 115. One or more communication protocols may be used forcommunication between the wear state monitors 50 of the brush holderassemblies 715 and the site monitor 720. The communication circuit 740may include a chipset capable of communicating via one or morecommunication link technologies such as by using audio energy (e.g. anultrasonic signal), radio frequency (RF) energy (e.g., an RF signal),and/or light energy (e.g., an optical signal, an infrared (IR) signal,etc.), or the like. In some cases, the communication circuit 740 may becapable of communicating via one or more other wireless technologiessuch as Bluetooth™, Wi-Fi, Zigbee or any other wireless protocol. Insome cases, the communication circuit 740 may be configured tocommunicate via one or more wired interfaces, but this is not required.For example, the communication circuit 740 may include a wired port suchas a serial port, an ARCNET port, a parallel port, a serial port, a CATSport, a USB (universal serial bus) port, and/or the like. In some cases,the communication circuit 740 may use one or more communicationprotocols, such as Ethernet, BACNet, LONtalk, DeviceNet, Profibus,ControlNet, etc., that may be used via a wired network or a wirelessnetwork. For example, the communication circuit 740 may be configured tocommunicate via one or more communication links 125, 127, 135, and 137,such as via the network 130, to a remote monitoring device 150, 160 at aremote site at a different geographical location than the site monitor720, such as the remote monitoring site 140. In some cases, thecommunication circuit 740 may be configured to communicate to anindustrial controller (e.g., a programmable logic controller) to providewear state information about one or more brush assemblies 715 to a user.

In some cases, each of the one or more brush assemblies 715 may beassigned a unique identifier, such as a communication address, tofacilitate communication with one or more of the site monitor 720 andthe remote monitoring device 150, 160. Each unique identifier may allowthe site monitor 720 and/or the remote monitoring device 150, 160 toassociate received wear state information with a particular brushassembly and/or portion of the rotating component 15 of a particularelectrical machine. These identifiers may use one or more namingconventions, as desired by a user. For example, the identifier may usean alphanumerical naming convention (e.g., brushassembly14, em1.ba10,machine1.row1.colum3, sitea.machine1.ba3, etc.), a numerical namingconvention (e.g., 1,2, 1.2.4, etc.), or an encoded naming convention(e.g., 0x0145CDEF, 11000, etc.).

In some cases, the identifiers may be used to identify a particularbrush assembly individually, (e.g., brushassembly24, 24, 0x18, 11000,etc.). The identifiers may also be used to associate the particularbrush assembly with a particular electrical machine and/or a particularsite (e.g., site1_machine3_brushassembly12, 1.3.12, 0x0111000C, 01 1100001100, etc.). The wear state monitor 50 may be configured to storethe identifier as a character string or as a numerically encoded value.For example, an alphanumerical identifier using an alphanumerical namingconvention may be stored and/or communicated as a character string.Identifiers using a numerical naming convention or an encoded namingconvention may be stored as one or more numbers (e.g., integers, etc.)that may be communicated as one or more integer values. In some cases,the identifier may be encoded into a single integer value (e.g., ahexadecimal encoded value, a binary encoded value, etc.). By using anencoded naming convention, the identification information may becommunicated as, for example, an integer value to minimize communicationtime. By minimizing communication time, energy usage may be reduced toextend the usable lifetime of the power source 460 of the wear statemonitor, the power source 792 of the site monitor, or both.

Identification information may be encoded and stored in and/ortransferred to a memory device such as, but not limited to, RAM, EPROM,EEPROM, flash memory, a hard drive, and/or the like. As an example, a16-bit word may be used to encode identification information, such thata first portion of the 16-bit word (e.g., the four most significantbits, such as 0xSSSS_mmmmbbbbbbbb) may be used to identify a particularsite, a second portion of the 16-bit word may be used to identify aparticular electrical machine at the particular site (e.g.,0xssss_MMMM_bbbbbbbb), and a third portion of the 16-bit word may beused to identify a particular brush assembly 715 associated with theparticular electrical machine (e.g., 0xssss_mmmm_BBBBBBBB). In thisillustrative example, the brush monitoring system 700 may include up tosixteen sites that may be numbered between 0 and 15 (e.g., 0x0 to 0xF inhexadecimal, 0000 to 1111 in binary, etc.), up to sixteen electricalmachines (e.g., numbered between 0 and 15, between 0x0 and 0xF inhexadecimal, between 0000 and 1111 in binary, etc.) associated to eachsite, and up to two hundred and fifty six brush assemblies 715 (e.g.,numbered between 0 and 255, between 0x00 and 0xFF in hexadecimal,between 00000000 and 11111111 in binary) associated with each of theeach of the electrical machines. For example, a particular brushassembly 715 may be assigned an identifier of 0x3A04, which may bedecoded by the site monitor 720 and/or the remote monitoring device 150,160 as the fourth brush assembly 715 on the tenth electrical machine atthe third site. These naming conventions are merely illustrative andother such naming conventions may be used and/or contemplated for anyparticular user site and/or installation.

The site monitor 720 may include the user interface 790 forcommunicating with a user. For example, the user interface 790 may beany suitable user interface that permits the site monitor 720 to displayand/or solicit information, as well as accept one or more userinteractions with the site monitor 720. For example, the user interface790 may permit a user to enter data such as threshold values associatedwith particular wear states, time interval values, diagnostic limits,conditions under which diagnostic limits may be suspended, responses toalerts, and the like. In some cases, the user interface 790 may allow auser to enter information to facilitate the use of environmental data bythe site monitor and/or the wear state monitors, such as temperature setpoints, humidity set points, and the like. These are just some examples.

The user interface 790 may provide diagnostic information about themachine, including the wear state information about brushes of the oneor more brush holder assemblies 715 and/or the rotating components ofthe electrical machine, to a user via a visual indication, an audibleindication, an email, an instant message, a text message or some othermessage to a user to alert the user of the wear state of the one or morecomponents of the brush holder assembly 715. Such information may beprovided via an internet gateway 170 or other device that is adapted tocommunicate over the internet or other wide area network, such as thenetwork 130. Such an alert may be provided to the user even when theuser is away from the site in which the brush monitoring system 100 islocated, such as to the remote monitoring device 150, 160 at the remotemonitoring site 140. In some cases, the user interface 790 may include adisplay and a distinct keypad. A display may be any suitable display. Insome instances, a display may include or may be a liquid crystal display(LCD), and in some cases a fixed segment display or a dot matrix LCDdisplay. If desired, user interface 790 may be a touch screen LCD panelthat functions as both display and keypad. In some instances, a touchscreen LCD panel may be adapted to solicit values for a number ofoperating parameters and/or to receive such values, but this is notrequired. In some cases, the I/O block 770 of the site monitor 720 mayinclude an interface for connecting one or more user interface devices,such as an external display, a keyboard, a pointing device (e.g., amouse, a trackball, etc.).

In some cases, the processor 750 may be configured to process wear stateinformation about a rotating component of the electrical machine 710received from the wear state monitors associated with the one or morebrush holder assemblies 715. For example, the processor 750 may operateusing an algorithm for processing wear state information received fromthe brush assemblies 715 to monitor the wear state information of theone or more brushes and/or the rotating component 15 associated with therotating portion 730 of the electrical machine. For example, theprocessor 750 may be capable of predicting a usable lifetime remainingfor each brush 24 by monitoring the received information over time. Insome cases, the processor 750 may process instructions to store thereceived wear state information into the memory 760. For example, eachof the one or more brush holder assemblies 710 may be associated with aparticular memory block 762, 764 for storing information about theparticular brush holder assembly 715.

The processor 750 may use the stored wear state information, along withany new wear state information, to determine diagnostic informationabout the electrical machine 710. For example, trend information and/orenvironmental information received from the brush holder assemblies 715may be used to determine whether one or more of the brush holderassemblies 715, the rotating component 15 and/or the rotating portion730 may be misaligned, with respect to one or more of the othercomponents of the electrical machine. In some cases, the site monitor720 may include one or more sensors 795, such as environmental sensors(e.g., a temperature sensor, a humidity sensor, etc.), and/or an I/Oblock 770 that may include one or more wire terminals for receivinginformation from one or more environmental sensors to provideenvironmental information (e.g., a temperature, a humidity, etc.) aboutthe environment at the site. Such information may be helpful indetermining trends and/or performing other diagnostic analysis on theelectrical machine.

The processor 750 may be programmed to receive wear state informationfrom the one or more brush holder assemblies 715 at predeterminedintervals. In some cases, the predetermined intervals may be fixed at aparticular value (e.g., once per day, once per week, etc.) and in othercases, the intervals may change after a particular wear state has beenreached. For example, the processor 750 may be configured to receivewear state information from the brush holder assemblies 715 at a firsttime interval, such as once per day, until one or more brushes and/orthe rotating component 15 reach a wear state approaching the replacementwear state. At that point, the processor 750 may sample the wear stateinformation from the brush holder assemblies 715 at a second shortertime interval, such as hourly. In some cases, the processor 750 mayinclude a timer 752 and/or may be communicatively coupled to a timercircuit.

In some cases, the site monitor 720 may receive information about theflexible sensors 60 included in the one or more brush holder assemblies715. For example, the wear state monitors of the brush holder assemblies715 may not include processing capability to determine a wear stateindication of the brush 24 and/or the rotating component 15. As such,the processor 750 of the site monitor 720 may be programmed to determinea wear state of at least one of the brush 24 and the rotating component15 using information received from one or more flexible sensors 60 ofthe brush holder assemblies 715. The processor 750 may, for example,operate using an algorithm that causes the communication circuit 740 toobtain information corresponding to a bend radius of the flexible sensor60 of a particular brush holder assembly 715 continuously or atpredetermined intervals. The processor 750 may then compare the receivedinformation to one or more predetermined threshold values to determine awear state indication for the brush 24 and/or the rotating component 15.

The memory 760 of the illustrative site monitor 720 may be incommunication with the processor 750. The memory 760 may be used tostore any desired information, such as the aforementioned controlalgorithm, threshold values, schedule times, sampling times, trendinginformation, and the like. As mentioned above, each of the one or morebrush holder assemblies 715 may be associated with a particular memoryblock 762, 764 for storing information about the particular brush holderassembly 715. The memory 760 may be any suitable type of storage deviceincluding, but not limited to, RAM, EPROM, EEPROM, flash memory, a harddrive, and/or the like. In some cases, the processor 750 may storeinformation within the memory 760, and may subsequently retrieve thestored information.

In some cases, the site monitor 720 may optionally include a data port780. The data port 780 may be a wireless port such as a Bluetooth™ portor any other wireless protocol. In other cases, data port 780 may be awired port such as a serial port, a parallel port, a CATS port, a USB(universal serial bus) port, and/or the like. In some instances, dataport 780 may be a USB port and may be used to download and/or uploadinformation from a USB flash drive or some other data source. Otherremote devices may also be employed, as desired. The data port 780 maybe configured to communicate with processor 750 and may, if desired, beused to upload information to processor 750 and/or download informationfrom the processor 750. Information that can be uploaded and/ordownloaded may include, for example, values of thresholds and/or timinginformation. In some instances, the data port 780 may be used to uploadpreviously-created configuration information of a particular electricalmachine 710 and/or a particular brush holder assembly 715, such as thewear state monitor 50 and/or the flexible sensor 60, thereby hasteningthe configuration process. In some cases, data port 780 may be used todownload a configuration that has been created using a particular wearstate monitor 50 and/or flexible sensor 60 so that the configuration maybe transferred to other similar wear state monitors 50, hastening theirprogramming process. In some cases, the data port 780 may be used toupload and/or download information pertaining to wear state trends ofthe brush 24 and/or the rotating component 15, if desired.

In some cases, data port 780 may be used to download data stored withinthe memory 760 for analysis. For example, data port 780 may be used todownload a wear state log associated with one or more brushes and/orrotating components to a removable device such as a USB memory stick(also sometimes referred to as a thumb drive or jump drive), personalcomputer, laptop, iPAD® or other tablet computer, PDA, smart phone, orother remote device, as desired. In some cases, the data may beconvertible to an MS EXCEL®, MS WORD®, text, XML, and/or Adobe PDF®file, but this is certainly not required.

FIG. 8 illustrates an exemplary bus of mounting blocks and brush holderassemblies 810a-d of an electrical machine utilizing differentconfigurations of the wear state monitor 812a-d and the flexible sensor815a-d. In some cases, one or more brush holder assemblies 810a-d may bemounted onto the electrical machine by mounting the brush holderassemblies 810a-d on mounting blocks secured to a stationary member 34.For example, a first brush holder assembly 810a may be mounted onto afirst mounting block, a second brush holder assembly 810b may be mountedonto a second mounting block, a third brush holder assembly 810c may bemounted onto a third mounting block, and a fourth brush holder assembly810d may be mounted onto a fourth mounting block, etc.

When the brush holder assemblies 810a-d are moved to the engagedposition (such as shown in FIGS. 3, 5A, and 5B) in which the electricalconnection is established through the brush 824a-d, a terminal and amounting block to/from the conductive surface 12, the wear statemonitors 812a-d may be positioned in an initial wear state position. Atsome later point in time, after the brush holder assembly 810a-d hasbeen installed on the electrical device and used, such as when a brush824a-d has worn sufficiently to warrant replacement, when an anomaly orthreshold condition has occurred, or otherwise when maintenance needs tobe performed on the electrical device, the brush holder assembly 810a-dand/or the brush 824a-d of the brush holder assembly 810a-d may beremoved from the mounting block and replaced with a new brush holderassembly 810a-d and/or brush 824a-d.

In some cases, the wear state monitor 812a-d and/or the flexible sensor815a-d may be configured differently. For example, the wear statemonitor 812a and 812d may include a slot-like opening, such as theopening 225 of FIG. 2. In such cases, the electrical connections of theflexible sensors 815a, 815d may be connected internally to the wearstate monitor 812a, 812d. In such cases, the flexible sensor 815a may beaffixed to the spring using an adhesive and may be coated with acoating, such as Teflon, to protect the flexible sensor 815a from wear.In another example, the wear state monitor 812d may be configured toextend beyond the edge of the spring 829d such that the flexible sensor815d may be positioned adjacent to the edge of spring 829d. In otherexamples, the flexible sensor 815b, 815c may include one or more wiredconnections that may be connected to the wear state monitor 812b, 812d.In the illustrative example of FIG. 8, the wear state monitor 812b mayinclude two terminals on the same end of the wear state monitor 812b.However, the wear state monitor 812c may include a terminal on each endof the wear state monitor 812b. These configurations are merelyillustrative and other such configurations may be used and/orcontemplated.

FIG. 9 shows a graph 900 of an illustrative voltage associated with thevariable resistance of the flexible sensor 60 associated with the wearstate of a brush 24 over time. As mentioned above, the flexible sensor60 may have a variable resistance that may vary based on a bendingradius applied to the flexible sensor 60. For example, if the bendingradius of the flexible sensor 60 increases, then the variable resistancevalue of the flexible sensor 60 would increases accordingly, accordingto a characteristic curve of the particular flexible sensor. As such,when the flexible sensor 60 is incorporated into an electrical circuit,such as a voltage divider circuit, the voltage output from the voltagedivider circuit may vary accordingly, as shown as the curve 910. In anexample, an initial variable resistance value 905 may be determined whena particular flexible sensor 60 is incorporated in a brush assembly 110that is in an engaged position. Over time, as the associated brush 24wears, the bending radius of the flexible sensor 60 will increase. Inthis particular voltage divider configuration, the voltage increases. Insome cases, at least two threshold voltages may be defined formonitoring the wear state of the brush 24. For example, the firstthreshold value, Vm 920, may be associated with a wear state approachinga replacement wear state and the second threshold value, Vr 930, may beassociated with the replacement wear state. In some cases, at the time940, an associated wear state monitor may indicate to a user that thebrush 24 has reached a wear state approaching the replacement wearstate. At time 950, the associated wear state monitor may indicate to auser that the brush 24 has reached the replacement wear state.

FIG. 10 shows a graph 1000 of an example of a transient voltage signal1010 illustrative of a condition of a rotating component 15 of anelectrical machine. In some cases, the transient voltage signal 1010 mayoperate under a shorter time scale than the steady state signal. Forexample, the wear state monitor 50 may monitor one or more transientevents occurring within a single revolution and/or over one or morerevolutions of the rotating component 15. For example, the time 1015 maycorrespond to a time of a single revolution. For a rotating component 15rotating at about 1000 revolutions per minute, a single revolution mayoccur about every 0.06 seconds. In some cases, the wear state monitor 50may monitor transient events over multiple revolutions (e.g., tworevolutions, five revolutions, ten revolutions, etc.). The transientevents 1025 may be correspond to a vibration of the brush, such as whenthe brush 24 encounters irregularities on the surface of the rotatingcomponent 15. In some cases, two or more threshold values may bedefined, such as Vmt 1020 and Vrt 1030, where Vmt 1020 corresponds to awear state when the rotating component 15 is approaching the replacementwear state and Vrt 1030 may correspond to a replacement wear state ofthe rotating component 15. As can be seen, the transient event 1035 hascrossed the Vrt 1030 threshold value. In such cases, the wear statemonitor may indicate that the rotating component has reached thereplacement wear state. In other cases, the wear state monitor mayindicate that the rotating component has reached the replacement wearstate after Vrt has been reached a specified number of times and/or fora specified duration. These are just some examples.

In some cases, some vibration having a small magnitude (e.g., about0.002 inches, about 0.003 inches, etc.) of the brush may be presentduring normal operation. As the rotating component 15 wears, themagnitude of the vibration may change. By monitoring the magnitude ofthe signal representative of the vibration (e.g., the transient voltagesignal 1010), the wear state of the rotating component may be inferred.For example, during normal operation vibration having a magnitude ofapproximately 0.005 inches or less may be considered “acceptable”. Asshown in FIG. 10, three wear state conditions may be inferred bymonitoring the transient voltage signal 1010. For example, a first area1040 may correspond to an “operational” wear state (e.g., vibrationmagnitude<about 0.005 inches), a second area 1050 corresponding to awear state approaching a replacement wear state (e.g., a vibrationmagnitude between about 0.005 inches and about 0.010 inches, and a thirdarea 1060 corresponding to a replacement wear state (e.g., a vibrationmagnitude>about 0.10 inches) may be defined using thresholds 1020, 1030.

FIG. 11 shows an illustrative method 1100 for monitoring a wear state ofone or more components of an electrical device. At 1110, a wear statemonitor may obtain a variable value from a flexible sensor, such as avariable resistance value, a variable voltage value and/or a variablecurrent value. The variable voltage value and/or the variable currentvalue may be associated with the variable resistance value of theflexible sensor. The variable value may be used to sense the movement ofa carbon brush in relation to a rotating component of an electricaldevice, such as a slip ring of the electrical machine of FIG. 7. Forexample, the variable resistance may correspond to a bend radius of theflexible sensor 60 associated with the brush 24 and spring 29 of thebrush holder assembly 110. Variations in bend radius may be associatedwith the movement of a brush and or a wear state of the brush inrelation to the rotating component of the electrical device. At 1120,the variable resistance value may be compared to a threshold value todetermine a wear state of the brush. The wear state of the brush may becommunicated to a user, such as by a user interface that may include avisible indicator and/or an audible indicator.

In some cases, at 1130 the indication of the wear state of the brush maybe communicated to a site monitoring device and/or a remote monitoringdevice. The remote monitoring device may be located at the same and/orat a different geographical location from the geographical location ofthe electrical machine and the site monitoring device.

In some cases, the wear monitor, the site monitor and/or the remotemonitoring device may include a processor capable of processinginstructions for predicting a life expectancy of the brush and/or therotating component of the electrical machine using the resistance valueassociated with the movement of the carbon brush. In some cases, theprocessor may be capable of processing instructions for identifying thewear state of the carbon brush using a steady state variable resistancevalue and/or identifying the wear state of the rotating electricalcomponent (e.g., a slip ring, a commutator, etc.) of the electricaldevice using a transient variable resistance value.

Those skilled in the art will recognize that aspects of the presentdisclosure may be manifested in a variety of forms other than thespecific embodiments described and contemplated herein. Accordingly,departure in form and detail may be made without departing from thescope and spirit of the present disclosure as described in the appendedclaims.

What is claimed is:
 1. A monitoring apparatus for monitoring a carbonbrush of a brush holder assembly of an electrical machine, the apparatuscomprising: a sensor configured to move with a spring of the brushholder assembly, the sensor having an output that varies as a shape ofthe sensor varies, wherein the shape of the sensor changes in responseto movement of the carbon brush in relation to a rotating component ofthe electrical machine; and a signal processing circuit coupled to thesensor to receive the output, the signal processing circuit configuredfor determining a measure of a wear state of the carbon brush usingoutput of the sensor, wherein the signal processing circuit ispositionable within a coiled portion of the spring.
 2. The monitoringapparatus of claim 1 21, wherein the sensor has a first shape uponinitial installation of the carbon brush in the electrical machine and asecond shape after a particular amount of wear to the carbon brush. 3.The monitoring apparatus of claim 1, wherein the movement of the carbonbrush is indicative of the wear state of the carbon brush and the sensormay be aligned along a plane after a particular amount of wear to thecarbon brush.
 4. The monitoring apparatus of claim 1 21, wherein theshape of the sensor that varies is a radius of curvature of the sensorthat changes in response to movement of the carbon brush in relation toa rotating component of the electrical machine.
 5. The monitoringapparatus of claim 4, wherein the sensor has a first radius of curvatureupon initial installation of the carbon brush in the electrical machineand a second radius of curvature after a particular amount of wear tothe carbon brush.
 6. The monitoring apparatus of claim 4, wherein theoutput is a voltage output.
 7. The monitoring apparatus of claim 6,wherein the voltage output varies as the radius of curvature of thesensor varies.
 8. The monitoring apparatus of claim 1 21, wherein thesensor includes a flexible resistor and the output of the sensor variesin response to an electrical resistance of the flexible resistorchanging due, at least in part, to changes in the shape of the sensor.9. The monitoring apparatus of claim 1, wherein the signal processingcircuit determines the measure of the wear state of the carbon brush bycomparing the output of the sensor to at least one predeterminedthreshold value.
 10. The monitoring apparatus of claim 9, wherein the atleast one predetermined threshold value corresponds to a steady statemeasure of the output of the sensor.
 11. The monitoring apparatus ofclaim 1, wherein the signal processing circuit determines the measure ofthe wear state of the carbon brush by comparing the output of the sensorto a first threshold value and determines a measure of a wear state ofthe rotating component of the electrical machine by comparing the outputof the sensor to a second threshold value.
 12. A brush holder assembly,the assembly comprising: a brush holder for receiving and positioning acarbon brush in relation to a rotating component of an electricalmachine; a spring mounted to the brush holder, the spring for providinga force to a carbon brush received in the brush holder such that thecarbon brush engages the rotating component of the electrical machine; asensor positioned between the spring and the brush holder, the sensorhaving an output that varies as a shape of the sensor varies, whereinthe shape of the sensor is representative of based on a physicalposition and/or movement of a carbon brush received in the brush holder;and a wear state monitor in electrical communication with the sensor,the wear state monitor positioned within a coiled portion of the spring,the wear state monitor for determining a measure of a wear state of thecarbon brush using the output of the sensor.
 13. The assembly of claim12, wherein the brush holder includes a mounting beam and the sensor ispositioned between the mounting beam and the spring.
 14. The assembly ofclaim 12 22, wherein the shape of the sensor that varies is a radius ofcurvature of the sensor that changes in response to movement of thecarbon brush in relation to a rotating component of the electricalmachine.
 15. The assembly of claim 14, wherein the output is a voltageoutput.
 16. The assembly of claim 15, wherein the voltage output variesas the radius of curvature of the sensor varies.
 17. The assembly ofclaim 12 22, wherein the sensor includes a flexible resistor and theoutput of the sensor varies in response to an electrical resistance ofthe flexible resistor changing due, at least in part, to changes in theshape of the sensor.
 18. The assembly of claim 12, wherein the wearstate monitor is further configured to determine a wear state of therotating component of the electrical machine using the output of thesensor.
 19. A brush holder assembly having an integral sensor formonitoring a wear state of a carbon brush or a rotating component of anelectrical machine, the brush holder assembly comprising: a brush holderhaving a mounting beam; a carbon brush positioned in the brush holder; aspring coupled to the brush holder, the spring for providing a force toengage the carbon brush with a rotating component of the electricalmachine; a sensor positioned between the spring and the mounting beam,the sensor having an output that changes as a change in radius ofcurvature of the sensor changes; an indicator for providing anindication of the wear state of at least one of the carbon brush and therotating component of the electrical machine based, at least in part, onthe output of the sensor.
 20. The brush holder assembly of claim 19,further comprising: a communication circuit, the communication circuitconfigured communicate information about the wear state of at least oneof the carbon brush and the rotating component of the electrical machineto a site monitor proximate to the electrical machine.
 21. Themonitoring apparatus of claim 1, wherein the output of the sensor variesas a shape of the sensor varies, wherein the shape of the sensor changesin response to movement of the carbon brush.
 22. The brush holderassembly of claim 12, wherein the output of the sensor varies as a shapeof the sensor varies, wherein the shape of the sensor changes inresponse to movement of the carbon brush.
 23. A monitoring apparatushaving a sensor for monitoring a wear state of a carbon brush of a brushholder assembly of an electrical machine, the monitoring apparatuscomprising: a sensor attachable to a spring of the brush holderassembly, wherein the sensor is configured to move with the spring; awear state monitor positionable within a coiled portion of the spring,wherein the wear state monitor is communicatively coupled to the sensorto obtain information about the wear state of the carbon brush based onmovement of the spring; and a power source disposed within the coiledportion of the spring to provide power to the wear state monitor. 24.The monitoring apparatus of claim 23, wherein the wear state monitorincludes a cylindrical body designed to be captured within the coiledportion of the spring.
 25. The monitoring apparatus of claim 24, whereinthe wear state monitor includes one or more ribs used to ensure the wearstate monitor remains mounted within the coiled portion of the spring.26. The monitoring apparatus of claim 23, wherein the wear state monitorincludes a communication circuit, the communication circuit forcommunicating information about a wear state of the carbon brush. 27.The monitoring apparatus of claim 26, wherein the communication circuitis capable of communicating via one or more wireless technologies. 28.The monitoring apparatus of claim 27, wherein the communication circuitis configured to wirelessly communicate the wear state of the carbonbrush to a site monitor proximate to the electrical machine.
 29. Themonitoring apparatus of claim 23, wherein the wear state monitorincludes a temperature sensor.
 30. The monitoring apparatus of claim 23,wherein the wear state monitor is configured to identify acharacteristic of a vibration of the carbon brush.
 31. The monitoringapparatus of claim 23, wherein the wear state monitor includes an energyharvester.
 32. A system for monitoring a wear state of a carbon brush ofa brush holder assembly mounted on an electrical machine, the systemcomprising: a wear state monitor positionable within a coiled portion ofa spring urging the carbon brush into engagement with a rotatingcomponent of the electrical machine; and a site monitor configured toreceive a signal from the wear state monitor indicative of a wear stateof the carbon brush; wherein the wear state monitor includes a powersource disposed within the coiled portion of the spring to provide powerto the wear state monitor.
 33. The system of claim 32, wherein the wearstate monitor is communicatively coupled to a sensor to obtaininformation about the wear state of the carbon brush.
 34. The system ofclaim 32, wherein the site monitor is configured to receive the signalfrom the wear state monitor wirelessly.
 35. The system of claim 32,wherein the wear state monitor is configured to monitor a vibration ofthe carbon brush and the site monitor is configured to notify a user ofexcess vibration of the carbon brush.
 36. The system of claim 32,wherein the wear state monitor includes a temperature sensor and thesite monitor is configured to notify a user of excess heating of thebrush holder assembly.
 37. The system of claim 32, wherein the wearstate monitor includes an energy harvester.
 38. A method for monitoringa wear state of a carbon brush of a brush holder assembly mounted on anelectrical machine, the method comprising: obtaining a signal from asensor attached to a spring of the brush holder assembly, the springurging the carbon brush into engagement with a rotating component of theelectrical machine, wherein the signal is proportional to linearmovement of the carbon brush relative to a brush holder of the brushholder assembly surrounding the carbon brush; processing the signal witha wear state monitor positioned within the coiled portion of the springto determine a wear state of the carbon brush, wherein the wear statemonitor includes a power source disposed within the coiled portion ofthe spring to provide power to the wear state monitor; and communicatingthe wear state of the carbon brush to a site monitor in proximity to theelectrical machine.
 39. The method of claim 38, further comprising:displaying an indication of the wear state of the carbon brush on adisplay of the site monitor.
 40. The method of claim 38, furthercomprising: displaying a predicted life expectancy of the carbon brushon a display of the site monitor.
 41. The method of claim 38, whereinthe signal varies based on movement of the sensor with the spring. 42.The method of claim 38, further comprising: monitoring a vibration ofthe carbon brush with the wear state monitor.
 43. The method of claim38, wherein the wear state monitor includes an energy harvester.
 44. Abrush holder assembly for monitoring a wear state of a carbon brush ofan electrical machine, the brush holder assembly comprising: a carbonbrush; a spring associated with the carbon brush, the spring applying aforce to a top surface of the carbon brush to engage the carbon brushwith a rotating component of the electrical machine; and a wear statemonitor positioned within a coiled portion of the spring; wherein thewear state monitor includes a power source disposed within the coiledportion of the spring to provide power to the wear state monitor. 45.The brush holder assembly of claim 44, wherein the wear state monitorincludes a cylindrical body designed to be captured within the coiledportion of the spring.
 46. The brush holder assembly of claim 44,wherein the wear state monitor includes a communication circuit, thecommunication circuit for communicating information about a wear stateof the carbon brush.
 47. The brush holder assembly of claim 44, whereinthe wear state monitor includes one or more environmental sensors,wherein the one or more environmental sensors includes a temperaturesensor.
 48. The brush holder assembly of claim 44, wherein the wearstate monitor is configured to identify a characteristic of a vibrationof the carbon brush.
 49. The brush holder assembly of claim 44, whereinthe wear state monitor includes an energy harvester.